a) Singleton methods are inserted into an anonymous class immediately 
above the object in the method lookup chain.

b) The methods in an included module are also inserted in an anonymous 
class immediately above the class/module that does the include()'ing.

One tricky part of the method lookup: class methods are inherited by 
subclasses:

class Parent
  def self.greet
    puts 'Hi!'
  end
end

class Child < Parent
  def self.cry
    puts 'Weeep, weep!'
  end
end

Child.cry
Child.greet

--output:--
Weeep, weep!
Hi!

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